Cracker has it about right, look there are tooooo many out of work/starving lawyers who will take any deep pockets or otherwise possible, settle out of court case. Even murderers and rapist shot in the act have had lawsuit filed for them.
A bad or accidental shooting on your part will be hard to justify and could possibly be made worse by some outrageous modifications, that might be construed as some type of gross negligence ( 1lb trigger on duty type gun.)
Your safest bet is to have any work done by the factory, then at least they may stand behind you if (BIG IF) something causes the gun to go off on its own(act of God).
Honestly no modification takes the place of serious, proper practice.Most self defense type shooters would be better of spending money for (good) training or ammo to shoot more on your own.
What sinks alot of cases, or at least gives them an opening are things like, undocumented/or no training,improper statements, like "I didnt mean to shoot" or such, and lying (in this day of cameras everywhere) will sink you alot faster, than a set of new tactical sights, or high powered ammunition.( READ this as KEEP MOUTH SHUT!)Learned that at an early age!!!
I had an example one day, certain gun distributer was selling guns with "THE BIG WHOMPER" laser etched on the slide, I advised a young guy that that may not be the best idea for a self defense weapon and why, though unhappy, he understood.
There are no positively safe or for sure rules, I've always gone by the old "rather judged by 12,than carried by 6 rule." MY 35 yr experience ..02 worth.
Good Luck , save your money, take care of your family, and maybe we will all servive the next 4 years. Merry Christmas. B